The BSF has increased the number of "sensitive and vulnerable" spots along the Indo-Bangladesh border in West Bengal and ramped up vigil there to check the influx of the Rohingyas into the country.

"Earlier we had identified 22 spots, but now we have increased it to 50. These are vulnerable and sensitive spots from where both Bangladeshis and Rohingyas can cross over. We have increased our vigil," PSR Anajaneyulu, IG, BSF (South Bengal), told PTI.

These sensitive locations are spread across North 24 Parganas, Murshidabad, and Nadia districts. All these spots fall under the South Bengal Frontier formation of the BSF.

Some of the vulnerable areas include Petrapole, Jayantipur, Haridaspur, Goalpara and Tetulberai.

According to BSF officials in the South Bengal Frontier, 175 Rohingyas were apprehended by the BSF in the last few years, of which seven were caught in 2017.

The BSF is also enhancing its local source base and working with different central agencies to identify and track the movement of the Rohingyas.

Of the 4,096-km-long Indo-Bangla border, 2,216.7 km is in West Bengal.

Terming the Rohingya refugees as "illegal" immigrants, the union government on September 18 had submitted before the Supreme Court that their continued stay posed "serious national security ramifications."

Thousands of Rohingyas, described by the UN in 2013 as one the most persecuted minorities in the world, fled their homes in Myanmar's Rakhine state recently to escape a military crackdown.